The present invention relates generally to optical position sensors for measuring the position of an object; or for detecting the interface between a clear and opaque liquid that are immiscible in each other, such as crude oil and water contained in a storage tank.
Water generally accompanies the production of crude oil. This bi-layered “liquid” is temporarily stored in tanks for eventual separation, with the oil going in one direction and the water in another. Knowing the position of the oil-water interface is important in preventing either the oil or the water from going where it should not during transfer to successive tanks.
The use of optical fibers or waveguides for fluid level sensors are attractive because they introduce no electrical energy into the storage container, are insensitive to electromagnetic interference, have no moving parts, can provide a continuous measurement of fluid level, and are generally low cost.